RE: iFCP vs FCIP

[Joshua Tseng <jtseng@NishanSystems.com>]

Hi Doug,

Good questions.

> 
> Joshua,
> 
> What advantage is there in combining routing functions 
> together with TCP

Whether to combine IP routing functions in the iFCP gateway is
an implementation choice.  iFCP only specifies the mapping of
Fibre Channel addresses to IP.  This allows dyanmic IP routing
to be accomplished in either the same iFCP gateway box or a
neighboring box such as a Cisco or Nortel switch.

Combining the routing in the same iFCP gateway doing the TCP 
encapsulation allows OSPF (or some other IP routing protocol)
to select alternate routes through the IP network between iFCP
gateways.  Load balancing is also a feature of OSPF.

> encapsulation?  Could you envision this with two proposals?  

Please clarify what you mean by two proposals.  You mean iFCP and
FCIP?  I do not know if we need two separate proposals...it depends
on what you want to achieve.  FCIP has very limited goals.  iFCP
is more comprehensive, and provides the framework to do end-to-end
switching and routing of Fibre Channel frames over an IP network.

> As most, if not
> all, FC devices are simple storage nodes with third party 
> commands, could
> you move routing to Copy Managers?  FC does not require the 
> extensibility of
> IP.  Are you envisioning the client to connect through FC?

Yes.  The Copy Manager client could connect through FC interfaces
on the iFCP gateway box.

> 
> Doug
> 
> 
> > Hi David,
> >
> > >
> > > I am no FCP expert so please correct me if I am wrong. In a pure
> > > FCP world, there is end-to-end traffic and there is 
> traffic that is
> > > destined to go between AS's. The primary difference is that there
> > > is an explicit route to the border gateways in the latter
> > > case. In both
> > > the proposals, within the FCP realm the addresses are FCP 
> based until
> > > they hit an edge node.  In iFCP the destination is 
> converted to an IP
> > > address that represents the end node address (which may 
> actually be
> > > a gateway back into FCP on the other side), in FCIP the request is
> > > routed to the other AS's FC border gateway and this request is
> > > encapsulated
> > > in a TCP request. Given that we are moving between AS's (I
> > > believe that
> > > is an assumption in FCIP) can we not use iFCP and instead of
> > > specifying
> > > the IP address of the end node, specify the IP address of the
> > > other AS's
> > > border gateway since FCP should already be doing some 
> encapsulation
> > > to route between AS's?
> > >
> > > 	-David
> >
> > Up until recently with the creation of the DMP routing protocol, the
> > concept of AS's (Autonomous Systems, right?) was foreign to Fibre
> > Channel networking.  Most Fibre Channel networks are 
> comprised of just
> > a handful of switches--the largest FC network I have ever heard of
> > being deployed is a 15 switch fabric.  Perhaps somewhere there are
> > some fabrics which are bigger, but probably not by much.
> > (Architecturally, a single Fibre Channel fabric has a 
> maximum capacity
> > of 239 switches)
> >
> > FCIP does not do anything to improve the scalability limits of
> > the Fibre Channel fabric.  All it does is allow extension of the
> > FC fabric over distances using an IP network.  The FCIP gateway is
> > completely invisible and non-intrusive to the Fibre Channel switches
> > and does not change or improve the scalability or interoperability
> > limits of FC fabrics.
> >
> > On the other hand, an iFCP gateway actively participates in
> > switching and routing traffic between FC fabrics and FC devices, by
> > mapping FC addresses to IP addresses and routing them using standard
> > IP routing protocols.  Using iFCP, a storage network has the same
> > scalability limits as any other IP network (e.g., IPv4 
> address space,
> > etc...).
> >
> > Josh
> >
>